mariposa lilies

genus Calochortus

Member of lily family (family Liliaceae)
monocots (class Liliopsida)
flowering plants (subphylum Angiospermae)

Except for old historical records and extremely rare examples that I don't expect to encounter, there are no other wild species of this genus in the bay area.
Caution: The key to distinguish these species is not complete.

Key features:

petal color and pattern
stem branching or not
bulblets present or not

yellow mariposa lily
Calochortus luteus

yellow mariposa lily
Calochortus luteus

corolla is deep yellow, with small red spots plus perhaps one central red blotch
nectary (yellow/orange spot amidst hair) is crescent-shaped or oblong

Key features for butterfly vs. clay:

stem is branched or not
pale second spot is above central dark spot or not
nectary is square or crescent shaped

butterfly mariposa lily
Calochortus venustus

butterfly mariposa lily
Calochortus venustus

nectary (yellow/orange spot amidst hair) generally ± square (discounting the curve of the petal), not in red spot
each petal has a central dark blotch, generally a 2nd paler blotch above
stem generally branched
tremendous potential variation in color; examples

clay mariposa lily
Calochortus argillosus

clay mariposa lily
Calochortus argillosus

nectary (yellow/orange spot amidst hair) is crescent shaped
each petal has a central dark blotch, but without a 2nd blotch above

dark blotch on petal is within pale yellow zone

anthers purple, pink to yellow-white
stem simple [but the inflorescence may be branched, which can be confusing]
fruit lanceolate [and angled?] [example]

superb mariposa lily
Calochortus superbus

arguably indistinguishable from clay mariposa lily (Calochortus argillosus)
dark blotch on petal is within bright yellow zone
anthers white to light yellow
fruit linear, angled [example]
no iNaturalist observations in the bay area

Calflora observations are dubious (e.g. photos with pale yellow zones)

tolmie’s pussy-ears
Calochortus tolmiei

tolmie’s pussy-ears
Calochortus tolmiei

petal not spotted or striped (but hairs on petal may be)
petal conspicuously hairy adaxially (on top)

petals pale purple

splendid mariposa lily
Calochortus splendens

petals uniformly pale purple
sparsely white-hairy near base of petal [upper surface]

oakland mariposa lily
Calochortus umbellatus

petals uniformly pale purple to white
stem 8–25 cm, branched, bulblets 0

pink star-tulip
Calochortus uniflorus

petals uniformly pale purple to white
stem generally < 5 cm, generally simple, bulblets present

alkali mariposa lily
Calochortus striatus

petals pale purple with dark purple radial stripes

tiburon mariposa lily
Calochortus tiburonensis

petals light yellow-green with significant amounts of purple-brown
Marin area

globe lilies

white globe lily
Calochortus albus

white globe lily
Calochortus albus

flower nodding, perianth ± closed, globe shaped
petals not yellow

diogenes’ lantern
Calochortus amabilis

flower nodding, perianth ± closed, globe shaped
petals deep yellow
plant ± glaucous
Mt. Tam area

mount diablo fairy-lantern
Calochortus pulchellus

flower nodding, perianth ± closed, globe shaped
petals light yellow
plant green
Mt. Diablo area

Toxicity of mariposa lily, sego lily (Calochortus spp.):
0 – Non-toxic.

5 observed taxons / 8 unobserved taxons / 1 key

Chris’s observations: 108 (106 are research grade)

Locations:

Months:

Apr.: 12
May: 52
Jun.: 37
Jul.: 5
Aug.: 1
Sep.: 1

For more details, use advanced search.

Taxon info: iNaturalist – Calflora – Jepson eFlora – FNA

Bay Area species: iNaturalist – Calflora